1. Field of the Invention
Embodiments of the present invention relate to an apparatus and method, e.g., a portable mobile device, protecting a recording and/or reproducing apparatus, and more particularly, to a portable mobile device and method protecting a hard disk drive (HDD) thereof, wherein a protection mechanism for an information processing unit is differently applied based on a portable state/non-portable state in the portable mobile device.
2. Description of the Related Art
As an example, a portable mobile device can include a notebook computer, an MP3 player, a digital camera, and a cellular phone, etc. Recently products have included information processing units, such as hard disk drives (HDDs) optical disk drives (ODDs), for example, in order to improve information storage capabilities.
However, a characteristic of the portable mobile device is that the portable mobile device is frequently moved. Further, there is always the potential of the portable mobile device falling and impacting a surface with sufficient force to damage the information processing unit. Additionally, HDDs have the disadvantage that their heads and disks are more vulnerable to such impacts.
Therefore, in a portable mobile device having a HDD it is desirable to protect the HDD from a movement that may damage the HDD or which may be representative of an acceleration, e.g., a falling, that may indicative of potential damage to the HDD.
When a head is positioned on a disk of a HDD, an air bearing is formed between a slider and the disk by air pressure of the rotating disk. Thanks to the air bearing, the slider can fly on the disk in a floating state.
During such a floating state, a motion of the head in a vertical direction at a center of the slider can be given by the following formula:
                    m        ·                              ⅆ            2                                ⅆ                          t              2                                          ⁢      z        -          ∫              ∫                              (                          P              -                              P                a                                      )                    ⁢                      ⅆ            x                    ⁢                      ⅆ            y                                =      -          F              s        ′            
Here, z is a movement amount in a vertical direction at the center of the slider, P is a pressure by Reynolds Equation, Pa is the ambient pressure, and m is a mass of the slider. If an impact greater than the design strength (Fsz) for the air bearing is applied to the HDD, the air bearing may be destroyed, causing the head and the disk to physically touch.
The air bearing of the slider in the HDD may be designed to prevent a physical contact between the head and the disk upon an impact of 200-300 G. Further, when the slider is positioned outside of the disk, with the heading being in an unloaded state, the head and the disk may be protected from an impact of more than 1000 G.
Therefore, protection from an impact is much greater when the head is unloaded from the disk rather than when the head is loaded on the disk.
FIGS. 1A and 1B schematically illustrate a loading/unloading of a head slider in a ramp loading type HDD. A ramp-loading type HDD 10 includes a ramp 6 and a projected portion 3b formed on an actuator 3. If an operating current is applied to a voice coil motor 5, the actuator 3 pivots along an operation axis 3a and the projected portion 3b slides across surfaces 6a through 6d of the ramp.
In FIG. 1A, an unloading direction is the clockwise moving direction of the actuator rotation and a loading direction is the counterclockwise moving direction of the actuator rotation. If the head slider 4 is unloaded and the actuator 3 is withdrawn from disk 1, the projected portion 3b formed on the actuator 3 first comes into contact with a parking surface 6d of the ramp. At this point, a coil supporting member 3c also touches or gets very close to an outer crash stop 7.
When the head slider 4 is loaded, the actuator 3 rotates to in the loading direction and transfers the head slider 4 onto the rotating disk 1. The projected portion 3b slides on the surfaces of the ramp 6, sequentially passes through the surfaces 6a through 6c of the ramp, and is finally detached from the inclined surface (parking surface) 6d. 
Conversely, when the head slider 4 is unloaded, the actuator 3 rotates in the unloading direction and transfers the head slider 4 onto the rotating parking position 6d. The projected portion 3b slides across the surfaces of the ramp 6 and sequentially passes through the surfaces 6a through 6c of the ramp and comes into contact with the parking surface 6d. 
In the meantime, unloading a head of a HDD based on whether a portable mobile device is carried, is known.
In particular, FIG. 2 schematically illustrates a method for protecting a HDD, in a portable mobile device including the HDD. FIG. 2 illustrates U.S. Patent Publication No. 2002-0126411, in which whether a cellular phone and a digital camera are carried is detected using a detection mechanism, and if the portable mobile device is not carried, the HDD is unloaded.
Referring to FIG. 2, when a cellular phone 20 is in a portable state, a HDD 10 normally operates. For example, the HDD 10 can perform its normal operations of recording and/or playing information to/from the hard disk. Conversely, when the cellular phone 20 is in a non-portable state, the HDD 10 is unloaded for its protection.
Whether the cellular phone 20 is carried is detected by an electrostatic detection sensor 21, with a control circuit 25 generating a control signal S controlling load/unload of the HDD 10 based on the detection results of the electrostatic detection sensor 21.
FIG. 3 illustrates an example of such an electrostatic detection sensor. The electrostatic detection sensor, as shown in FIG. 2, judges whether the portable device is within proximity of a human body, i.e., whether the apparatus is being carried, using an intensity of an electrostatic potential between electrodes A and B.
The detecting of such a potentiality an impact, a falling down, a vibration, and corresponding unloading of a head of a HDD, if necessary, in order to secure safety of the HDD are known.
In particular, such technology is intended to protect a HDD from impact, a fall, and vibrations, as disclosed in Japanese Patent Publication Nos. 2000-99182 (published as of Apr. 7, 1999) and 2002-8336 (published as of Jan. 11, 2002).
FIG. 4 illustrates a typical HDD protection circuit using an acceleration sensor. More specifically, FIG. 4 illustrates the HDD protection circuit disclosed in Japanese Patent Publication No. 2003-263853. Referring to FIG. 4, a head collision prevention circuit 42 detects whether a movement speed of a HDD is faster than a critical speed, and an actuator operating circuit 44 controls whether a HDD is unloaded based on detection results of the head collision prevention circuit 42.
FIG. 5, similarly, further illustrates the acceleration sensor shown in FIG. 4. The acceleration sensor 50 can include a pendulum 52 and a piezo element 54 attached to the pendulum 52. The pendulum 52 may be moved in x, y, or z directions depending on movement of a HDD, and an intensity of an electrical signal detected by the piezo element 54 varies as the pendulum 52 moves. Accordingly, it is possible to compute the degree of a movement of the pendulum 52 in x, y, or z directions using the electrical signal from the piezo element 54.
An important desire of a portable mobile device including a HDD is to efficiently protect the HDD as well as guaranteeing optimum performance of the HDD.
Since it may be impossible to take measures whatsoever before an impact is applied when using simply a shock sensor, it is difficult to efficiently protect a HDD against such an impact. Conversely, using an acceleration sensor, it is possible to estimate the protection need of a HDD using the falling speed and moving speed, e.g., before impact. Accordingly, using the acceleration sensor is more effective than the shock sensor.
However, even though it may be judged that a protection measure needs to be implemented for protection of the HDD, based on the acceleration sensor, such a measure may deteriorate operation performance of a portable mobile apparatus if the protection measure is indiscriminately applied without consideration as to a portable state or a non-portable state of the portable mobile device.
For example, if a portable mobile device is being carried, even if movement of some extent is indicated, there exists only an extremely small probability that a corresponding impact or fall may actually reach a level sufficient to cause damage to the HDD. Therefore, in that case, to guarantee operation performance of the HDD, it may be more beneficial to delay an unloading of the HDD. Further, with consideration of the above-described context, it may also be understandable that operation performance may not be guaranteed if a HDD is unloaded due merely because the portable mobile device is not being currently carried.
Therefore, there is a need for an improved method for taking measures to protect a HDD based on whether a portable device is carried and the degree of a movement to guarantee operation performance and safety at the same time in the portable mobile device.